September 1977
Every planar map is four colorable. Part I: Discharging
K. Appel, W. Haken
Illinois J. Math. 21(3): 429-490 (September 1977). DOI: 10.1215/ijm/1256049011
First Page PDF
JOURNAL ARTICLE
62 PAGES
Vol.21 • No. 3 • September 1977
